1. Field of the Invention
The present invention relates to a storage medium having stored therein an image recognition program for recognizing a predetermined image object from an image captured by an image-capturing section, an image recognition apparatus, an image recognition system, and an image recognition method.
2. Description of the Background Art
There are conventional techniques for detecting a predetermined image object from an image (captured image) captured by an image-capturing section such as a camera. For example, Non-Patent Document 1 (Hirokazu Kato, Mark Billinghurst, Koichi Asano, Keihachiro Tachibana, “An Augmented Reality System and its Calibration based on Marker Tracking”, Journal of Virtual Reality Society of Japan, Vol. 4, No. 4, 1999) describes performing an image recognition process on a marker included in an image captured by a camera in an augmented reality technique. In Non-Patent Document 1, connected regions are extracted by binarizing the captured image using a fixed threshold value, and those of the connected regions with an appropriate size and shape are selected as marker candidates, which are subjected to pattern matching so as to detect a marker.
With the recognition method described in Non-Patent Document 1, the image recognition process is performed by pixels of the captured image as input. Therefore, when the input image has a high resolution (high definition), the amount of time required for the image recognition process is increased. On the other hand, if the image recognition process is simply performed with a lower precision (at coarser pixel pitches) than the pixel pitch of the input captured image, the marker detection precision is lowered.